A pointer-compressed heap has the same heap limit heuristics as a 32-bit
heap. Specifically, the heap limit is restricted to 1GB due to scarce
virtual addresses space on 32-bit platforms. That limitation does not
apply for pointer-compressed heaps which can use 4GB.

This CL changes the heap limit computation to use system the pointer
size instead of the tagged pointer size. Note that the young generation
limit continues to use the tagged pointer size.

Bug: chromium:1045034
Change-Id: I9d5bb818c32a82322476e9c97feee331400ebe0f
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2042102Reviewed-by: Igor Sheludko <ishell@chromium.org>
Commit-Queue: Ulan Degenbaev <ulan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#66159}

The new API function is called ConfigureDefaultsFromHeapSize and
accepts two parameters: the initial and the maximum heap size.
Based on the given limits the function computes the default size
for the young and the old generation.

The patch also cleans up the existing functions to make them
consistent in terms of units and heap structure.

Bug: v8:9306
Change-Id: If2200a9cdb45b0b818a373207efe4e6426f7b688
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1631593
Commit-Queue: Ulan Degenbaev <ulan@chromium.org>
Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#62017}